Hi Gary,gmarsh said:
Yes, AVR Studio 4 running the AVRISP MkII erases, and programs the ATMEGA8, and then exits the programming mode successfully, but they cannot read the flash after programming is completed.
I was sort of hoping that the second one would behave differently so I would know I had a fault on the first board somewhere .....something to look for.
Since they are both behaving identically, I'm not sure where the problem is, but it does not seem to affect the operation of the HD-1s at all.
Robert
Havent buildt it yet but,is there anyone taken the signal direct from the DAC to input to an amplifier?
Hi Ryssen,
Gary partially addressed this idea in Post No. 54 on this thread. Apparently there is a significant DC offset at the OPA output that would have to be delt with. It is still an interesting idea though, to be able to selectively bypass the head amp and use the unit as a DAC only.
Any circuit wizzards out there who might suggest a mod? I am currently working on my third board and would be interested in such a mod if it could be done.
Robert
Gary partially addressed this idea in Post No. 54 on this thread. Apparently there is a significant DC offset at the OPA output that would have to be delt with. It is still an interesting idea though, to be able to selectively bypass the head amp and use the unit as a DAC only.
Any circuit wizzards out there who might suggest a mod? I am currently working on my third board and would be interested in such a mod if it could be done.
Robert
Third board hmmm.I vonder how you do when you solder those small Ic:s,I have only soldered some SO8,how do you do not to short the pins?
How small are your tip?
How small are your tip?
For soldering the ICs and the other very small 0603 SMDs, I use soldering paste that has the solder and the flux mixed together (Mouser and DigiKey both have it).
I use a microscope and a very small screwdriver to apply small amounts of the paste directly to the pads, then tweezers to set the components into the paste daps. I have a Weller digital iron with the smallest pencil tip they make, and I set it at a pretty high temperature....about 760 deg. F. so it fuses very quickly.
After I'm done with a small group of components, I look at it under the microscope again to make sure I have all good joints, and no bridges.
Also, I do the ICs last, so I can clean all the flux off the boards from the rest of the SMDs with flux remover without fear of damaging the ICs with the flux remover.
I know this is an unconventional technique, but it works quite well.
Robert
I use a microscope and a very small screwdriver to apply small amounts of the paste directly to the pads, then tweezers to set the components into the paste daps. I have a Weller digital iron with the smallest pencil tip they make, and I set it at a pretty high temperature....about 760 deg. F. so it fuses very quickly.
After I'm done with a small group of components, I look at it under the microscope again to make sure I have all good joints, and no bridges.
Also, I do the ICs last, so I can clean all the flux off the boards from the rest of the SMDs with flux remover without fear of damaging the ICs with the flux remover.
I know this is an unconventional technique, but it works quite well.
Robert
If you don't mind having the TPA chip in the signal chain, the headphone jack has single ended audio on it. 😉Ryssen said:
If your amplifier can accept balanced audio, yank the TPA chip and tag onto the outputs of the OPA2134 chip for your balanced signal, bringing it to a pair of XLR's. Assuming a 681 ohm I/V resistor, there is a DC offset voltage here of -4.2 volts, and a swing of +-2.6v volts on top of this. Make sure your amplifier can accept a signal this big.
As far as soldering goes, I didn't use solder paste to build mine. Surface mount resistors/capacitors, the TPA chip and other 'big' items were soldered using a fine tip soldering iron and thin fluxless solder off a roll with paste flux. I used a popsicle stick to hold the part in place during soldering. To solder the TSSOP's, I've got a cavity dremelled into a tip from my Hakko 936 station, creating a clone of a Pace "Mini-Wave" tip. I flux up the pads on the PCB, lay the part in place and "sweep" the solder-filled tip across the pins.
I used water soluble flux. After soldering the SMT's only, the whole board was cleaned in an ultrasonic bath at work. Then the through-hole parts were installed.
Oh; to remove the DC offset from the balanced outputs while still maintaining DC coupling...
Use another quad op-amp; an OPA2134 or whatever configured as four inverting amps with a gain of 1, driven with the four outputs of the existing OPA2134. Instead of grounding the + as you'd normally do with an inverting amp, set it to -2.1V using a programmable shunt regulator like a LM4041.
Use another quad op-amp; an OPA2134 or whatever configured as four inverting amps with a gain of 1, driven with the four outputs of the existing OPA2134. Instead of grounding the + as you'd normally do with an inverting amp, set it to -2.1V using a programmable shunt regulator like a LM4041.
I finished my two boards today. 😀 So far it seems very good, but I will let them play for a couple of days and see then.
Andy
Andy
Voltage Problem?
Okay.....I was not careful finishing up my 3rd board (the first two went without a problem). I accidentally put a 12v regulator in the 3.3v section of the PSU that serves the CS8416, and did not notice it until after I powered up. Now the HD-1 has no output.
The CS8416 lists the maximum power supply voltage as 3.46v on VA+ and VD+, and 5.5v on VL+. Between the 7.5v transformer, rectifier with an output at about 10.6v, and the regulator at 12v, I'm guessing I hit the receiver with at least the 10.6v. Is it likely to be fried?
The Atmega8 also feeds off of the 3.3v section, but it still seems to accept programming okay......should I consider replacing it as well?
Also, the AD8611 and Torx142L also use the 3.3v....would they be susceptible to damage from over-voltage also?
Or, finally, are my over-voltage concerns unfounded and I should be looking elsewhere for the problem.....I have checked all my passive component values and looked at all of the soldering under a microscope with no apparent problems.
Thanks for anyones input.
Robert
Okay.....I was not careful finishing up my 3rd board (the first two went without a problem). I accidentally put a 12v regulator in the 3.3v section of the PSU that serves the CS8416, and did not notice it until after I powered up. Now the HD-1 has no output.
The CS8416 lists the maximum power supply voltage as 3.46v on VA+ and VD+, and 5.5v on VL+. Between the 7.5v transformer, rectifier with an output at about 10.6v, and the regulator at 12v, I'm guessing I hit the receiver with at least the 10.6v. Is it likely to be fried?
The Atmega8 also feeds off of the 3.3v section, but it still seems to accept programming okay......should I consider replacing it as well?
Also, the AD8611 and Torx142L also use the 3.3v....would they be susceptible to damage from over-voltage also?
Or, finally, are my over-voltage concerns unfounded and I should be looking elsewhere for the problem.....I have checked all my passive component values and looked at all of the soldering under a microscope with no apparent problems.
Thanks for anyones input.
Robert
Follow Up
I have checked the PSU section outputs at C44 thru C47 and all are now within .1v of the correct values. I also checked the voltages at most of the IC and crystal V inputs and they were all okay as well.
I have replaced the CS8416, Atmega8, Torx, and AD8611 with no results.
Is it possible to check the crystal output with my Fluke RMS Meter somehow to see if it was damaged?
Robert
I have checked the PSU section outputs at C44 thru C47 and all are now within .1v of the correct values. I also checked the voltages at most of the IC and crystal V inputs and they were all okay as well.
I have replaced the CS8416, Atmega8, Torx, and AD8611 with no results.
Is it possible to check the crystal output with my Fluke RMS Meter somehow to see if it was damaged?
Robert
Thanks Gary,gmarsh said:
I was aware of that and was considering swapping those out also as my next move.
Unfortunately I hit another little setback. I was playing around with the AVR programmer to make sure I had correct programming, and somehow managed to set the RSTDSBL and EESAVE fuses in the new Atmega8. The fuses and lockbits are now all wrong, and my Avrisp can no longer access it. I'm trying to figure out how to perform a fuse erase/reset, but this stuff is very new to me. The Atmega8 datasheet lists PC6 as a RESET pin, and the AVRSP manual lists pin 5 of the interface connector as reset, but I'm not sure how to 'draw the voltage to a low level', or if this would even accomplish a fuse reset. I'm about to contact ATMEL support to see if it can be done.
If not, I have one more Atmega8 left, but I would rather not de-solder it again....this board is a little fragile for repeated re-works.
Once I get the Atmega programming fixed again, I will probably swap the remaining 3.3v devices because I have checked and re-checked everything else I can think of.
I was hoping to get all three HD-1s cased up before Christmas, as 2 of them are earmarked as gifts.....I love the two that are working!
Robert
Once you disable RSTDSBL, you can't re-enable it unless you do high voltage programming... and do that, you'll need a STK500 and a lot of flying wires soldered to the board.
Pull the chip, and be careful with the fuses!
Pull the chip, and be careful with the fuses!
Thanks Gary......I was beginning to think that was the case as I read more in the data sheets.
I really don't know how I got it screwed up, but you can bet I will be careful next time......with the regulators too!!!! I had actually stored the regulators in the wrong little poly bag and did not verify them before soldering in.
Robert
I really don't know how I got it screwed up, but you can bet I will be careful next time......with the regulators too!!!! I had actually stored the regulators in the wrong little poly bag and did not verify them before soldering in.
Robert
Atmega8
Well, this is just weird now. I have replaced all of the ICs, Ocillator, etc., put in a new Atmega8, and the programmer immediately defaulted to the fuses that do not allow further programming.....I never even tried to program it. Reading the fuses and lockbits confirms that they were already programmed with the incorrect settings.
I checked the programmer with my other two HD-1s, and they are fine.....reads the correct lockbits and fuses no problem.
So I put in yet another Atmega8 (my last one), and it did exactly the same thing. It's seems like they were pre-programmed with the incorrect fuses set. I'm beginning to wonder if I got a batch of bad Atmegas.....they are not from my original order that I used to build my first two boards. I had to order some additional ones when I got the spare board directly from Gary.
I've order a few more, but they will be week or so.
Robert
Well, this is just weird now. I have replaced all of the ICs, Ocillator, etc., put in a new Atmega8, and the programmer immediately defaulted to the fuses that do not allow further programming.....I never even tried to program it. Reading the fuses and lockbits confirms that they were already programmed with the incorrect settings.
I checked the programmer with my other two HD-1s, and they are fine.....reads the correct lockbits and fuses no problem.
So I put in yet another Atmega8 (my last one), and it did exactly the same thing. It's seems like they were pre-programmed with the incorrect fuses set. I'm beginning to wonder if I got a batch of bad Atmegas.....they are not from my original order that I used to build my first two boards. I had to order some additional ones when I got the spare board directly from Gary.
I've order a few more, but they will be week or so.
Robert
do you have the Mega8 device type set correctly?
It just occured to me that with the "reset disabled" fuse set, ISP won't even work - you even can't read fuses to tell they're wrong.
It just occured to me that with the "reset disabled" fuse set, ISP won't even work - you even can't read fuses to tell they're wrong.
Yes....Studio 4 has 'Device' set for the Atmega8. I even removed and reinstalled the program from my computer to be sure I hadn't corrupted it somehow. The weird thing is that it works fine with my other two boards....I even took a chance and programmed one of them again....works fine.gmarsh said:
I can have the fuses and lockbits preset to the correct values, and as soon as I plug in my 3rd board, the fuses and lockbits default to the incorrect values.....thereby preventing re-programming.
Robert
I finally got around to casing up my first two HD-1s. I used the taller Hammond case to avoid trimming the transformer and regulator tab. It fits in with room to spare, and about the 4th slot up centers the vol pot and jacks perfectly.
My third HD1 is still a problem. I have replaced the Atmega8 three times, and each time it seems to auto-program with the incorrect fuses before I ever command the programming. I must have a problem with one of the other components that is interfering with the programming, but I cannot figure out what.....I have replaced all the other ICs once after I got my voltage issue corrected.
The first two are awsome, and one will be a Christmas gift to my son.
Robert
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
My third HD1 is still a problem. I have replaced the Atmega8 three times, and each time it seems to auto-program with the incorrect fuses before I ever command the programming. I must have a problem with one of the other components that is interfering with the programming, but I cannot figure out what.....I have replaced all the other ICs once after I got my voltage issue corrected.
The first two are awsome, and one will be a Christmas gift to my son.
Robert
Check the ISP frequency in the "Board" tab of the ISP programming window... set it to something low (15KHz or so), if this is set too fast you'll get weird things happening.
Before you start writing fuses or programming, do the "Read Signature" thing in the Advanced tab and make sure you see "Signature matches selected device".
Before you start writing fuses or programming, do the "Read Signature" thing in the Advanced tab and make sure you see "Signature matches selected device".
Thanks Gary. That was a problem alright....the ISP frequency on the 'board tab' was defaulting to 1MHz when I would leave that tab, and the signature did not match the selected device on the advanced tab. I reset the ISP frequency to 5.875khz (if I recall correctly), programmed it in, then everything else programmed and verified perfectly after that. So the Atmega8 seems to be functioning properly now.gmarsh said:
Unfortunately I am still getting no sound except a small thump at power on and power off, so I must have another fault of some kind that I have not found. Are there signal test points along the signal path that I could safely sample to see how far it is going? I have a Fluke 187 true rms meter.
Thanks, Robert
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